D_Cide Traumerei the Animation.

The story takes place in Shibuya. Ryuhei had always looked up to his older brother as a child. Even after witnessing his mysterious death, Ryuhei grows up to be a cheerful high school student. One day after his daily kickboxing practice, he is bitten by a strange creature calling itself Tris. That night, an unusual dream bothers his sleep. As the rumored "Drops" circulate around the city, Ryuhei is confronted with a force of twisted desire. What is it that awaits him beyond that?